Blaschko lines, invisible stripe patterns on everyone’s skin, can sometimes produce different amounts of melanin. Birds may also be able to see them, even if we can’t.
Discover the viral sensation spreading across the internet. Check out the community’s top reactions below.
Top Reddit Reactions
“Can these be seen with the help of some sort of tool? I want to see my pattern.”
“Because a lot of people don’t seem to be understanding, here’s how ~~im pretty sure~~ they work: the lines are descended from how early fetal cells spread over the body during development, e.g. in the picture the lighter areas came from one patch of fetal cells and the dark areas came from another. This pattern happens in everybody, but is completely invisible except in the rare cases those different areas of fetal cells had genetic differences, such as in the image, where again one patch produced more melanin than the other leading to visibly darker skin following the lines.
It’s a common misconception that birds and cats can see them even without these differences, likely stemming from the fact that the lines *are* visible in the coats of some cats. Early in the fetal development of all female mammals one of the two X chromosomes becomes deactivated, which one is chosen is random on a per–cell basis. Because the coat colour of cats is encoded on the X chromosome, and which chromosome is kept active spreads along these lines, they are clearly visible in the coats of tortoiseshell and calico cats. This is the reason tortoiseshells and calicos are almost exclusively female, two X chromosomes with different colours are required to produce those coat patterns”
“Hey so why the fuck can birds see themselves and how do we know?”